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From waltersu4...@apache.org
Subject hadoop git commit: HDFS-10182. Hedged read might overwrite user's buf. Contributed by zhouyingchao.
Date Mon, 28 Mar 2016 07:48:07 GMT
Repository: hadoop
Updated Branches:
  refs/heads/branch-2 2b1f066d2 -> 07b0abe0b


HDFS-10182. Hedged read might overwrite user's buf. Contributed by zhouyingchao.

(cherry picked from commit d8383c687c95dbb37effa307ab2d41497da1cfc2)


Project: http://git-wip-us.apache.org/repos/asf/hadoop/repo
Commit: http://git-wip-us.apache.org/repos/asf/hadoop/commit/07b0abe0
Tree: http://git-wip-us.apache.org/repos/asf/hadoop/tree/07b0abe0
Diff: http://git-wip-us.apache.org/repos/asf/hadoop/diff/07b0abe0

Branch: refs/heads/branch-2
Commit: 07b0abe0b31f0f113428fe095e83d953be7b7a8d
Parents: 2b1f066
Author: Walter Su <waltersu4549@apache.org>
Authored: Mon Mar 28 15:44:25 2016 +0800
Committer: Walter Su <waltersu4549@apache.org>
Committed: Mon Mar 28 15:46:01 2016 +0800

----------------------------------------------------------------------
 .../java/org/apache/hadoop/hdfs/DFSInputStream.java | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/hadoop/blob/07b0abe0/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
index 5d0744e..040055e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
@@ -1329,7 +1329,7 @@ public class DFSInputStream extends FSInputStream
         // chooseDataNode is a commitment. If no node, we go to
         // the NN to reget block locations. Only go here on first read.
         chosenNode = chooseDataNode(block, ignored);
-        bb = ByteBuffer.wrap(buf, offset, len);
+        bb = ByteBuffer.allocate(len);
         Callable<ByteBuffer> getFromDataNodeCallable = getFromOneDataNode(
             chosenNode, block, start, end, bb,
             corruptedBlockMap, hedgedReadId++);
@@ -1340,7 +1340,9 @@ public class DFSInputStream extends FSInputStream
           Future<ByteBuffer> future = hedgedService.poll(
               conf.getHedgedReadThresholdMillis(), TimeUnit.MILLISECONDS);
           if (future != null) {
-            future.get();
+            ByteBuffer result = future.get();
+            System.arraycopy(result.array(), result.position(), buf, offset,
+                len);
             return;
           }
           DFSClient.LOG.debug("Waited {}ms to read from {}; spawning hedged "
@@ -1378,13 +1380,9 @@ public class DFSInputStream extends FSInputStream
           ByteBuffer result = getFirstToComplete(hedgedService, futures);
           // cancel the rest.
           cancelAll(futures);
-          if (result.array() != buf) { // compare the array pointers
-            dfsClient.getHedgedReadMetrics().incHedgedReadWins();
-            System.arraycopy(result.array(), result.position(), buf, offset,
-                len);
-          } else {
-            dfsClient.getHedgedReadMetrics().incHedgedReadOps();
-          }
+          dfsClient.getHedgedReadMetrics().incHedgedReadWins();
+          System.arraycopy(result.array(), result.position(), buf, offset,
+              len);
           return;
         } catch (InterruptedException ie) {
           // Ignore and retry


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